Last updated: April 9, 2010
Source: Associated Press in Washington via South China Morning Post
Scientists may have found a way to tell which smokers are at greatest risk of developing lung cancer: measuring a telltale genetic change inside their windpipes.
A test based on the research now is being developed, in hopes of detecting the deadly cancer earlier, when it is more treatable.
If the work pans out, the next big question is: might it even be possible to reverse this genetic chain reaction before it ends in full-blown cancer? The researchers found a tantalising early hint among a handful of people given an experimental drug.
“They’re heading towards lung cancer, and we can identify them with this genomic test,” said Dr Avrum Spira of Boston University School of Medicine, who led the research published on Wednesday in Science Translational Medicine.
Lung cancer is the world’s leading cancer killer, and cigarette smoke is its main cause. Yet, not all smokers develop lung cancer; Spira cites estimates that 10 to 20 per cent will.
The risk depends in part on how much people smoke, for how long and how long ago they quit, but there is no way to predict who will escape it and who will not. Nor is there a good way to detect early-stage tumours. Consequently, most people are diagnosed too late for today’s treatments to do much good.
Rather than focusing on the lung itself, Spira’s team hunted for the earliest signs of impending lung cancer upstream, in how different genes are turned on and off inside the upper airway as the body tries to defend itself and those defences weaken over time.
Every year at least 100,000 smokers or former smokers have tubes snaked down their throats to look for signs of cancer if an X-ray or other tests detect something suspicious, Spira explained. A bronchoscopy can be used for a look into the lung, but Spira was interested instead in cells that line the windpipe, collected during the same procedure.
Sure enough, he found a genomic signature – a pattern of gene activity – in otherwise normal windpipes that distinguished some current or former smokers who had lung cancer from those who did not.
Spira cannot estimate how much lung cancer might be due to this genetic pathway. Nor does the work mean it is all right for people without this marker to keep puffing. Other lung cancer pathways could be at work, and smoking also causes heart attacks, other lung diseases and other cancers.
But a company Spira helped found, Allegro Diagnostics, is beginning a study of up to 800 current and former smokers to see how well a test based on the research performs.
Moreover, there are some experimental drugs being designed to fight the genetic activity in question. One compound already had been tested in nine smokers with precancerous lesions, six of whom had their lesions improve.